Alkylene-functionality in bridged and fused nitrogen-rich poly-cyclic energetic materials:Synthesis,structural diversity and energetic properties

From the standpoint of chemical structures,the organic backbones of energetic materials can be classified into aromatic rings,nonaromatic rings,and open chains.Although the category of aromatic energetic compounds exhibits several advantages in the regulation of energetic properties,the nonaromatic heterocycles,assembling nitramino explosophores with simple alkyl bridges,still have prevailed in benchmark materials.The methylene bridge plays a pivotal role in the constructions of the classic nonaromatic heterocycle-based energetic compounds,e.g.,hexahydro-1,3,5-trinitro-1,3,5-triazine(RDX)and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX),whereas ethylene bridge is the core moiety of state-of-the-art explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20).In this context,it is of great interest to employ simple and practical bridges to assemble aromatic and nonaromatic nitrogen-rich heterocycles,thereby expanding the structural diversity of energetic materials,e.g.,bridged and fused nitrogen-rich poly-heterocycles.Furthermore,alkyl-bridged poly-heterocycles highlight the potential for the open chain type of energetic materials.In this review,the development of alkyl bridges in linking nitrogen-rich heterocycles is presented,and the perspective of the newly constructed energetic backbones is summarized for the future design of advanced energetic materials.

α-Oxo Ketene Dithioacetals Chemistry-A Facile Route to the Synthesis of Fused Heterocyclic Compounds

The fused heterocyclic compounds 2 : imidazo [1.2-a] pyriding 2a-c and pyrido [ 1 .2-a] pyrimidine 2d were obtained from the reaction of α-cinnamoyl ketene dibenzylthio acetals 1 with diamine. When α-cinnamoyl -a'-benzoyl ketene N. N-acetals 3a-b were treated by t-BuONa/t- BuOH Solution. 8- benzoyl-pyrido[1.2-a] pyrimidine 4 was produced.

SYNTHESIS OF FUSED PHOSPHORUS HETEROCYCLIC COMPOUNDS(II)

Using cation exchange resin(D72,Amberlyst-15) as catalyst, Mannich-type reaction of 5-amino-1,2,4-triazole 1, containing guanidine substructure, provides an efficient synthesis of a new kind of bicyclic P- and N-containing compounds, 6-phospha-4,5,6-trihydroimidazolo [2,3-e] 1,2,4-triazole 4.

A Convenient Method for the Synthesis of 1,3,2-Oxazaphospholidin-[3,2-a]-8-oxo-10-thio(or seleno)-[1,3,2]-benzodiazaphosphorines

A Convenient method for the synthesis of fused phosphorusheterocycle 1,3,2-oxazaphosphorin-[3.2-a]-8-oxo-10-thio(or seleno)-[1,3,2]-benzodiazaphosphorines was carried out in one pot by the reaction of Tris(diethylamino)phosphine with multifunctional compounds 2-(N-(beta or gamma-hydroxyl) alkylene) amino-benzamides 1. When PCL3 was used, only chlorinated product was obtained.

Copper-Catalyzed Cascade Acylation/Coupling Cyclization Process for the Synthesis of Polycyclic Fused Imidazo[2,1 -b] [1,3]th iazi n ones

A new and efficient cascade synthesis of polycyclic fused imidazo[2,1-b][1,3]thiazinones has been developed. This protocol includes an intermolecular N-acylation followed by a copper-catalyzed intramolecular C--S coupling reaction. The methodology is applied to a wide range of 2-iodo, 2-bromo, and 2-chloro benzoyl chlorides to yield the polycyclic fused imidazo[2,1-b][ 1,3]thiazinones in good to excellent yields.

Synthesis of fluorescent multisubstituted polyquinolines by cascade C–H activation-based polyannulations of isonicotinamides and diynes

The development of new and efficient polymerization strategies for the synthesis of multisubstituted fused heterocyclic polymers with attractive properties is of great significance.Herein,a rhodium-catalyzed polyannulation route is developed for the in situ generation of multisubstituted polyquinolines with efficient aggregate-state fluorescence.Based on the cascade C-H activation of isonicotinamides and their annulations with internal diynes,a series of high molecular weight polyquinolines are efficiently produced in high yields of up to 99%in a facile and atom-economical manner.Unlike conventional two-component stepwise polymerizations,these polyannulation reactions are tolerant to monomer non-stoichiometric conditions and proceed even more thoroughly in the presence of an excess amount of the isonicotinamide monomer.Benefiting from the unique multisubstituted polyquinoline structures,the obtained polymers show high thermal and morphological stability,useful aggregation-induced emission(AIE)properties,and tunable aggregated-state fluorescence behaviors.The AIE-active polyquinoline is demonstrated to be a good lysosome-specific fluorescent probe with low cytotoxicity and excellent photostability.

Cyclization of 4,5-Diamino Pyrazole Derivatives and Their Antibacterial Activities

A convenient synthesis of intermediate 4,5-diamino-3-aryl-l-phenylpyrazoles 4a--4c was reported. The different cyclization reactions were carried out with chalcone, 2-mercaptoacetic acid and p-anisialdehyde, ethyl chloroformate, glyoxal and thiourea to afford different N and S containing heterocycles. The reaction conditions were compared by conventional heating and microwave irradiation. The structures of the cyclization products were de- termined by analytical and spectroscopic data. All the synthesized compounds were screened for antibacterial activities in vitro.